But the U.S. Supreme Court blocked the request Monday night, scoring a win for the Trump administration, which wants the question on the 2020 U.S. Census. The case will go to trial Nov. 5.
The decision shields Ross from answering questions about adding the citizenship question to the census.
"Most censuses in our history have asked about citizenship, and Commerce Secretary Wilbur Ross recently decided to reinstate a citizenship question in the 2020 Census, citing a statement from the Department of Justice indicating that citizenship data would help it enforce the Voting Rights Act of 1965," Justices Neil Gorsuch and Clarence Thomas wrote in their opinions.
They went on to say that it's "highly unusual" to depose someone to see what their motivations were and if they acted in bad faith. There was no record of how the Supreme Court voted, though it would take five justices to grant the request.
The Supreme Court decision overrules an appeals court that said Ross would have to testify.
The court will allow Department of Justice officials such as Assistant Attorney General John Gore and others to be deposed.
The New York attorney general and the American Civil Liberties Union joined other states in suing the federal government, saying the question is meant to scare immigrant populations from participating in the census.
The mandatory census count is done every 10 years to determine how many people live in a given area. The data is used to determine how many lawmakers a state will have in the House of Representatives.
"The addition of the citizenship question is a naked act of intentional discrimination directed at immigrant community of color that is intended to punish their presence, avoid their recognition, stunt their growing political power and deprive them and the communities in which they live of economic benefits," the plaintiffs said in court documents.
U.S. Attorney General Jeff Sessions argues that the census has had a question in one form or another for more than 100 years.
"The words on the page don't have a motive; they are either permitted or they are not," Sessions said. "But the judge has decided to hold a trial over the inner workings of a cabinet secretary's mind."
Plaintiffs argue that a citizenship question hasn't been on the census since 1950.